Integrated power modules for plasma processing systems

Details Integrated power modules for plasma processing systems Integrated power modules for plasma processing systems

1998-11-12

2001-04-24

Leja, Ronald W. (Department: 2836)

Electricity: electrical systems and devices

Electric charge generating or conducting means

Use of forces of electric charge or field

C361S601000

Reexamination Certificate

active

06222718

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to plasma processing systems for use in the manufacture of semiconductor integrated circuits. More particularly, the present invention relates to improved plasma processing system IPMs (integrated power modules) that offer improved reliability and lower acquisition/maintenance costs.
Plasma processing systems have long been employed in the manufacture of semiconductor devices (such as integrated circuits or flat panel displays). In a typical plasma processing system, the substrate (e.g., the wafer or the glass panel) is typically disposed inside a plasma processing chamber for processing. Energy in the form of AC, DC, RF, or microwave is then delivered to the plasma processing chamber to form a plasma out of supplied etchant or deposition source gases. The plasma may then be employed to deposit a layer of material onto the surface of the substrate or to etch the substrate surface.
As the electrodes require energy to ignite and sustain the plasma, a power delivery system is typically required to condition the AC power obtained from the grid, to transform the AC power into the appropriate form of energy required to ignite and sustain the plasma, and to provide the DC voltages for operating the control electronics.
To facilitate discussion,
FIG. 1
illustrates a simplified power delivery system of a currently available plasma processing system known as the 4520XL™, available from Lam Research Corporation of Fremont, Calif. In the example of
FIG. 1
, plasma processing system
100
represents a parallel plate, multiple frequencies plasma processing system. It should be appreciated, however, that the discussion herein is not limited to this specific type of plasma processing system. In fact, the concept discussed herein is applicable to plasma processing systems in general irrespective of the number of electrodes, the geometry of the chamber, or the type of energy source employed. Further, although only one chamber of plasma processing system
100
is shown to facilitate discussion, it should be appreciated that a plasma processing system may take the form of a cluster tool, which may include one or multiple modules, each of which may have one or multiple chambers per module.
Referring now to
FIG. 1
, wafer
102
is shown disposed in a plasma processing chamber
104
for processing. More specifically, wafer
102
is shown disposed on a chuck
106
, which acts as one electrode. The other electrode
108
is disposed above wafer
102
as shown. RF generator
110
represents a 27 MHz RF generator, which supplies RF energy to match a network
114
through a coax cable
122
. As is well known, one function of the match network is to match the impedance of the plasma to that of the generator in order to maximize power delivery. From match network
114
, the RF energy is provided to electrode
108
through a diplexer
118
. A diplexer is a well known device that passes energy of a certain frequency while passing energy having other frequencies to ground. Since electrode
108
is a 27 MHz electrode, diplexer
118
passes 27 MHz RF energy to electrode
108
while passing RF energy having other frequencies to ground.
Likewise, RF generator
112
represents a 2 MHz RF generator which supplies the RF energy to match network
116
through coax cable
124
. From match network
116
, the RF energy is supplied to a diplexer
120
through coax cable
126
. Diplexer
120
passes 2 MHz RF energy to chuck
106
and passes RF energy having other frequencies directly to ground.
Nowadays, the various major functional blocks of a power delivery system (e.g., generators, matches, diplexers, or the like) are typically distributed among multiple subsystems, many of which are enclosed in their own EMI enclosures and include their own DC power supplies. This is because the current practice in power delivery system design is to render the major functional blocks or subsystems as modular as possible. In other words, the current practice is to provide each subsystem with sufficient local resources onboard (e.g., DC power supplies to operate the local electronics) so as to enable a given subsystem to be readily adapted for use in a plug-and-play fashion in many different plasma processing systems. By commoditizing these subsystems, the vendors of these subsystems hope to achieve economy of scale since fewer subsystems need to be designed and inventoried for the plasma processing equipment market.
There is also another design philosophy in the semiconductor processing equipment industry which favors the provision of resources required by each subsystem (e.g., DC power supplies) in the subsystems themselves. As plasma processing systems become more complex and expensive, lower cost of ownership is achieved by reducing the amount of time that the plasma processing system is out of service due to equipment failures. Beside improving the quality of the subsystems, vendors of plasma power delivery systems believe that by distributing the resources among the various modular subsystems, the effects of a subsystem failure can be isolated and addressed quickly. By making the subsystems modular and self-sufficient in terms of required resources, the failed subsystem can be swapped out, and the plasma processing system can be brought back into operation quickly.
As a practical matter, each of these modular subsystems (e.g., match networks
114
and
116
, diplexers
118
and
120
and RF generators
110
and
112
) occupies a nontrivial amount of space. Accordingly, it is oftentimes impractical to position these subsystems close to the plasma processing chamber and still provide adequate space for maintenance. The crowding problem is exacerbated in a cluster tool environment where multiple chambers may be positioned in close proximity to one another.
In the prior art, the crowding problem is addressed by moving certain subsystems to a remote location and to connect the subsystems together via conductors/or and coax cables. With reference to
FIG. 1
, for example, RF generators
110
and
112
, along with their water cooling systems and control electronics, may be positioned away from the plasma processing chamber to relieve crowding. In the typical case, RF generators
110
and
112
may be installed on a rack some distance away (50-60 feet in some cases) from the plasma processing chamber. Other subsystems such as matches and/or diplexers may be located closer to chamber
104
within the assembly shown as plasma processing module
150
. Coax cables
122
and
124
are then employed to couple the RF generators on rack
152
to the subsystems at plasma processing module
150
.
Because the subsystems of the power delivery system are now split among multiple locations, separate power distribution boxes are required. With reference to
FIG. 1
, rack
152
requires a power distribution box
154
to receive AC power from the grid (e.g., in the form of 208 volts, 3-phase) and to distribute AC power to RF a generators
110
and
112
via conductors
156
and
158
. These conductors
156
and
158
plug into RF generators
110
and
112
, which are provided with complementary plugs for quick connection and disconnection. Generator
110
also includes an additional connector for connecting with coax cable
122
(which supplies the RF energy to match network
114
). Likewise, RF generator
112
also includes an additional connector to couple with coax cable
124
(which supplies the RF energy to match network
116
).
DC voltages to the control electronics within RF generators
110
and
112
are provided by DC generators, which are typically provided onboard each RF generator to satisfy modular design guidelines. In the example of
FIG. 1
, RF generator
110
is shown having a DC power supply
162
for converting the AC voltage received at RF generator
110
to the DC voltages levels required by its control electronics. Likewise, RF generator
112
is shown having a DC power supply
164
for converting the AC voltage received at RF generator
112
to the DC voltage levels requi

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